The present invention is directed to a daisy wheel printer which accommodates different type wheel fonts.
At the present time present daisy wheel type impact character printers are designed to accept substantially one basic type of print wheel character font. This is because the printer either by a read only memory or by supplementary externally programmed instructions must provide with each particular character font instructions as to the hammer intensity, ribbon increment and carriage displacement. The carriage displacement is especially important when proportional spacing is utilized.
One attempted solution which has been tried in the past where it was desired to use print wheels one of which has an English alphabet and the other an Arabic alphabet was a double size read only memory was provided with a toggle switch on the frame of the printer which would switch between either of the memories depending on which character font was being used, English or Arabic. Rather than using a switch it was also possible to cut or reconnect a jumper wire or for that matter merely to replace one ROM with another.
In the specific case of the Arabic alphabet the ROM utilized only even printing positions and left seven possible even character positions blank in order to provide for extra space larger than usual for adjacent Arabic characters.
However, all of the foregoind was done on the bases of 96 printing positions and, of course, this is a standard in the industry for the daisy wheels.
Because of the above 96 character print wheel standard and the associated 96 printing positions provided by the daisy wheel drive system of the printer, print wheel designers have been severely constrained.
In a copending application entitled "Rotary Print Wheel System" in the name of Willy J. Grundherr, Ser. No. 700,654, filed June 28, 1976, and now U.S. Pat. No. 4,118,129 there is described a print wheel system which includes a print wheel drive which is capable of 192 printing positions. This 192 printing position system has actually been used with a so-called "documentary print wheel" where in order to provide proportional spacing, odd printing positions as well as even were used. However, this so-called documentary printing wheel which is shown in FIG. 3 was never used in a switchable mode. On contrary, the use of the documentary system severely restricted the use of any other wheel on this particular printer.
As is apparent from the foregoing, the capability of a daisy print system where the print wheel may be driven to substantially double the number of printing positions as the typical maximum number of characters on the print wheel has never been fully utilized.